If you are not sure which proxy server to use, try pinging each one individually (for example, issue the command ping proxy.lax.broadvice.com in a command prompt) and select the one with the shortest ping times. Then enter that proxy address in the X6v's Outbound Proxy and Register Domain fields.

For a screenshot of an example configuration, click ATA_Broadvoice.jpg in the File Attachments area below.